An offshore turbine is finally spinning in the United States! It's not the kind you're imagining, but this is a milestone nonetheless: The Ocean Renewable Power Company announced that its TidGen tidal turbines have started providing power to a utility grid owned by Bangor Hydro Electric Company. This marks the first time that any offshore power generation facility has fed electricity back to a utility grid in the United States.

ORPC completed installation of one of its tidal power devices earlier this summer in Cobscook Bay, part of the bigger Bay of Fundy, off the Maine coast. The TidGen has a peak power output of 180 kilowatts, enough to power around 25 to 30 homes. The company plans on installing another two turbines in the same location in the fall of 2013, possibly scaling up after that to 5 megawatts of power. That would be enough to power around 1200 homes.

The TidGen device, installed in water depths of 15 to 30 meters, takes advantage of water flowing in and out of the bay as the tides change. The Bay of Fundy as a whole is an enormous tidal power resource; ORPC says that 100 billion tons of water flow in and out of the bay every day, with tidal ranges as high as 15 meters. And tidal power has one advantage over, say, offshore wind energy, in that it is remarkably consistent and predictable. Ocean technologies in general are on the rise of late, such as the progress toward wave power in Oregon. Combined, wave and tidal power have fairly massive potential, up to as much as 15 percent of the U.S. electricity demand according to reports from the Department of Energy. Last year, a Georgia Tech group created a tidal power mapping tool that was validated by the DOE to aid in specific site development and localized resource assessment.